The macula densa is an important regulatory portion of the nephron. Located where the thick ascending limb of Henle's loop contacts the glomerulus, the macula densa plays a role in transmitting information about tubular fluid composition to the glomerulus, and afferent and efferent arterioles, thereby effecting changes in renal blood flow, renin release, and glomerular filtration rate. A rather rare integrin, the beta6 subunit, is expressed in the macular densa, particularly during development of the kidney. Since the macula densa has an important role in regulating function of the kidney, the study of a protein such as the beta6 integrin that is highly expressed in this region may provide clues to the development and regulation of the macula densa. To investigate the hypothesis that beta6 integrin is important in macula densa development and functin, the complete cDNA sequence of the mouse homologue of beta6 integrin will be determined and antibodies to the beta6 integrin extracellular and cytoplasmic, domains developed. These antibodies will be used to examine the expression pattern of beta6 integrin in the developing kidney, to isolate macula densa cells, and to evaluate the functional role of beta6 integrin in the macula densa.